Use a crab when harvesting gems. Simply wait for it to unearth a good haul (sometimes over 25 red gems and 40 blue gems) then grab the mole with the crab, take the gems, get back on and throw the mole away and fly (well jump good) to safety. Remember no matter how far away the mole who dug up the gems will get angry when they pick them up BUT other moles only aggro with it if they are close when you pick up the gems, or hit the mole.